1. Field of the Invention
The present invention relates to a tourniquet for temporarily occluding a patient's vein. More particularly, the present invention relates to a tourniquet which may be placed in circumscribing relationship about a patient's limb and which generates a signal after a predetermined period of time indicating that the tourniquet is still in place about the patient's limb.
2. Description of Related Art
A tourniquet is typically used to occlude a patient's vein and enable medical personnel to successfully perform a variety of intravenous procedures. Such procedures include routine medical procedures as a phlebotomy, intravenous catheter insertion, dialysis, blood transfusion, donation, intravenous therapy and infusion set insertion.
Common tourniquets which have been long used for this purpose include a length of elastic material which is circumferentialy placed about the patient's limb and secured and tightened in circumscribing a relationship therearound. Preferably, the tourniquet is secured about the patient's arm by slip knotting the tourniquet or by employing fastening members which may be attached to the tourniquet.
In typical use, a medical technician or phlebotomist will normally place the tourniquet about the upper arm of a patient and apply pressure by tightening. The tourniquet is then fastened in its tightened position to induce swelling in the veins of the lower arm. This causes a vein to stand out providing a convenient site for venepuncture. Once the site is identified, a needle is inserted, the blood sample is removed and the needle is withdrawn. After inserting the needle into the vein, or immediately after withdrawing of the blood, the tourniquet is promptly removed from the patient's arm. Removal of the tourniquet reestablishes proper blood flow through the patient's limb.
Leaving the tourniquet in place over an extended period of time, results in prolonged venostasis which may lead to an increased incidence of pre-analytical errors, unexplained analytical results, as well as discomfort and potential long term injurious results to the patient. The prompt removal of the tourniquet from the patient's limb is typically left to the memory of the medical technician conducting the procedure or to the patient from whom the blood is drawn. In certain situations due to distractions which may commonly occur in hospital and laboratory settings, it may be possible for the tourniquet to remain on the patient longer than is desirable.
Certain tourniquets have been developed which allow selective pressure levels to be applied to the patient's limbs. Many of these tourniquets provide pressure monitors to monitor the pressure applied to assure that it falls within a predetermined minimum and maximum pressure level. If the pressure falls outside the predetermined range, the sensor may emit an alarm alerting the technician. However, these pressure monitoring devices require complex mechanical and electrical equipment such as electrical wires, gauges, pressure supply lines and the like. None of these devices may be employed in a disposable tourniquet situation.
Therefore, it is desirable to provide an inexpensive throw-away or disposable tourniquet which can be easily used and which would avoid problems experienced with leaving the tourniquet in place over an extended period of time.